Fuel supply structure of working machine

ABSTRACT

In a fuel supply structure of a working machine according to the present invention, a hollow connection box which also serves as a sub-tank is integrally formed at a lower end portion of a filler neck which forms a fuel supply port. A connection port is formed in one side wall of the connection box and a fuel supply pipe is connected to the connection port. According to this construction, a suitable direction for connection of the filler neck and the fuel supply pipe can be selected and thus it is possible to enhance the piping freedom.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a fuel supply structure of aworking machine.

[0003] 2. Description of the Related Art

[0004] In a hydraulic excavator, a fuel tank and a filler neck whichforms a fuel supply port are disposed apart from each other and areconnected with each other through a fuel supply pipe.

[0005] In this case, straight connections are formed respectively in thefiller neck and the fuel supply pipe and are connected with each otherthrough a joint, or as is disclosed in Japanese Patent Application LaidOpen No. 2001-288778, the connection of the filler neck is formed ratherlong, then the fuel supply pipe is fitted thereon and is fixed using aband.

[0006] In both cases, the filler neck is in an upwardly elongated state,so that the direction of connection with the fuel supply pipe is alsolimited to the vertical direction. Consequently, it is required that thepipe be bent forcibly from the connection toward the tank.

[0007] Thus, for the connection of the filler neck and the fuel supplypipe, it is necessary to ensure at least the length of the straightportion (from an upper end of the filler neck to a lower end of theconnection of the fuel supply pipe) for connection of the two plus thelength required for minimum bending of the fuel supply pipe. In aworking machine without having a sufficient space in the verticaldirection and difficult to ensure a sufficient connection height, it isnecessary to change the layout of devices, thus resulting in the pipingfreedom becoming narrow and the piping work becoming troublesome.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide a fuel supplystructure of a working machine capable of enhancing the piping freedom.

[0009] The fuel supply structure of a working machine according to thepresent invention comprises, as a basic construction, a fuel tank, afuel supply conduit having a fuel supply port at its one end, and ahollow connection box formed at and in communication with the other endof the fuel supply conduit. The connection box has a projecting portionfor connection which acts as a connection port. Further provided is afuel supply pipe connected to the projecting portion for connection andcommunicating with the fuel tank.

[0010] According to this construction, the fuel supply pipe is connectedto the connection box and therefore its connecting direction can beselected from among various directions; for example, it may be adirection in which the connection can be done most easily, or adirection in which the distance up to the tank is the shortest. Thus, itis possible to widen the piping freedom.

[0011] Particularly in a small-sized working machine without having asufficient space for installation of devices, including such as engineand tanks, the piping work becomes easier.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a sectional view of a connection between a filler neckand a fuel supply pipe in a first embodiment of the present invention;

[0013]FIG. 2 is a perspective view showing an integral combination asone unit of the filler neck and a connection box in the firstembodiment;

[0014]FIG. 3 is a diagram corresponding to FIG. 1, showing a secondembodiment of the present invention; and

[0015]FIG. 4 is a diagram corresponding to FIG. 1, showing a thirdembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Fuel supply structures of a working machine according to thepresent invention will be described hereinunder with reference to FIGS.1 to 4.

[0017]FIG. 1 is a sectional view of a connection between a filler neck12 as a fuel supply conduit and a fuel supply pipe 15, showing a firstembodiment of the present invention. The fuel supply pipe 15 isconnected to a fuel tank T, while the filler neck 12 has a fuel supplyport 11 for refueling or the replenishment of fuel. A connection box 13for connection between the filler neck 12 and the fuel supply pipe 15 isformed at a base end portion Bower end portion) of the filler neck 12 soas to communicate with the fuel supply port 11. More specifically, theconnection box 13 is integrally formed as one unit with a projectingportion 14 for connection which acts as a connection port, and the fuelsupply pipe 15 is connected to the projecting portion 14 for connection.The projecting portion 14 is for connection of the fuel supply pipe 15.Therefore, it is optional from which of inner and outer surfaces of theconnection box 13 the projecting portion 14 is to be projected, insofaras it permits connection thereto of the fuel supply pipe 15.

[0018] The tank T may be arranged in such a manner that the tank T islower than the box 13 by bending the pipe 15 although the tank T isarranged nearly side by side with the box 13 as described in FIG. 1.

[0019] In FIG. 1, the connection box 13 is in the shape of a somewhatflat, hollow rectangular parallelepiped, but no limitation is madethereto. The filler neck 12 and the connection box 13 are molded intoone unit using a resin material such as a plastic material. By so doing,the manufacturing cost can be reduced despite the construction includingthe connection box 13.

[0020] In the first embodiment illustrated in FIGS. 1 and 2, theprojecting portion 14 for connection is formed on one side wall of theconnection box 13. The fuel supply pipe 15 is connected substantiallyhorizontally to the projecting portion 14 for connection. Since theprojecting portion 14 for connection is formed on a side wall of theconnection box 13, the filler neck 12 and the fuel supply pipe 15 arenearly perpendicular to each other so as to be nearly orthogonal to eachother through the projecting portion 14 for connection.

[0021] Since the filler neck 12 and the fuel supply pipe 15 are thusconnected perpendicularly to each other through the box 13, theconnection height is much smaller than in the conventional case. This isadvantageous particularly to a machine wherein it is difficult to ensurea sufficient space in the vertical direction.

[0022] On the other hand, in a second embodiment illustrated in FIG. 3,a projecting portion 14 for connection is formed on a bottom wall of theconnection box 13, and the fuel supply pipe 15 is connected verticallyto the projecting portion 14 for connection.

[0023] In both first and second embodiments, as to a concrete positionon the side wall (side face) or the bottom wall (bottom face) of theconnection box 13 where the projecting portion 14 is to be formed, itcan be set arbitrarily.

[0024] As the fuel supply pipe 15 there may be used a conventional fuelhose such as a rubber hose or a molded plastic hose called molded hose.Further, it is optional whether the fuel supply pipe 15 is to be fittedon the projecting portion 14 for connection and then fixed using a bandor it is to be connected to the projecting portion 14 for connectionwith use of a joint.

[0025] In FIGS. 1 and 3, the numeral 16 denotes a strainer which isdisposed within the connection box 13 so as to face the fuel supply port11, and numeral 17 denotes a cap which covers the fuel supply port 11.The strainer 16 eliminates foreign matters contained in fuel which isreplenished.

[0026] Thus, the fuel supply pipe 15 may be connected to not the fillerneck 12 but the connection box 13. Therefore, the direction in which thefuel supply pipe 15 is to be connected may be selected and determinedarbitrarily from substantially horizontal direction (longitudinal andtransverse directions in FIGS. 1 and 2) and substantially verticaldirection (FIG. 3) from a desired standpoint, for example from thestandpoint that piping is easiest or the distance to the tank T isshortest.

[0027] That is, unlike the prior art, the connecting direction is notlimited to the vertical direction, but it is possible to widen thepiping freedom. Besides, it is not necessary to bend pipe forcibly.Thus, the piping work is simplified even in a small-sized workingmachine such as a compact excavator or an excavator of a small rotatingradius type.

[0028] Particularly, in the first embodiment illustrated in FIGS. 1 and2, the fuel supply pipe 15 is connected nearly perpendicularly(horizontally) to the filler neck 12 through the box 13. Consequently,length from the upper end of the filler neck 12 to the lower surface ofthe connection box 13 suffices as the height (connection height) Hrequired for the said connection. This connection height is much smallerthan in the prior art. This is advantageous to a working machine whereinit is difficult to ensure a sufficient space in the vertical direction.

[0029] The connection box 13 can play the role of a sub-tank whichstores a portion of fuel, whereby it is possible to substantiallyincrease the capacity of the fuel tank T (by 500 cc or so for example).

[0030] Further, since the connection box 13 as a large volume chamberlies just under the fuel supply port 11, it is possible to preventbubbling during the supply of fuel and hence improve the efficiency ofthe fuel supply work.

[0031] Next, FIG. 4 illustrates a third embodiment of the presentinvention. As shown in FIG. 4, the filler neck 12, the connection box 13and the fuel supply pipe 15 may be formed as an integrally moldedcombination by integral molding of a plastic material. By so doing, themanufacturing cost can be reduced despite the construction including theconnection box 13. Further, in the case where the connecting directionsof the filler neck 12 and the fuel supply pipe 15 are determined inadvance, the operation for connecting the two is not needed, so that thepiping work is greatly simplified.

[0032] In the above embodiments the filler neck 12 and the connectionbox 13 are constituted as an integrally molded combination or one unitof a plastic material, but if they are to be made of metal, both may beformed separately and then combined by welding for example.

[0033] Though not shown, the connection box 13 may be formed with pluralprojecting portions 14 for connection. In this case, it is optionalwhether the projecting portions 14 for connection are to be formed onthe same surface or on different surfaces. Of course, they may be formedon both (substantially horizontal and vertical directions). In thiscase, the filler neck 12 and the fuel supply pipe 15 may be connectedtogether through a connection port which is suitable for piping,depending on each machine, and the other connection port may be closedwith lid. As a result, one connection box 13 can cope with variousdirections.

[0034] Although the invention has been described with reference to thepreferred embodiments in the attached figures, it is noted thatequivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims.

I claim:
 1. A fuel supply structure of a working machine, comprising: afuel tank; a fuel supply conduit having a fuel supply port at its oneend; a hollow connection box formed at and in communication with theother end of the fuel supply conduit, said connection box having aprojecting portion for connection which acts as a connection port; and afuel supply pipe connected to said projecting portion for connection andcommunicating with said fuel tank.
 2. The fuel supply structure of aworking machine according to claim 1, wherein said projecting portionfor connection is formed on a side wall of said connection box, and saidfuel supply pipe is connected to said projecting portion for connectionin such a manner that said fuel supply pipe is nearly perpendicular tosaid fuel supply conduit.
 3. A fuel supply structure of a workingmachine, comprising: a fuel tank; a fuel supply conduit having a fuelsupply port at its one end; a hollow connection box welded to the otherend of said fuel supply conduit and communicating with said fuel supplyport, said connection box having a projecting portion for connectionwhich acts as a connection port; and a fuel supply pipe connected tosaid projecting portion for connection and communicating with said fueltank.
 4. The fuel supply structure of a working machine according toclaim 1, wherein said fuel supply conduit and said connection box areformed of resin and are molded into one unit.
 5. The fuel supplystructure of a working machine according to claim 1, wherein said fuelsupply conduit, said connection box and said fuel supply pipe are formedof resin and are molded into one unit.